/*
 * Tencent is pleased to support the open source community by making Angel available.
 *
 * Copyright (C) 2017 THL A29 Limited, a Tencent company. All rights reserved.
 *
 * Licensed under the BSD 3-Clause License (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 *
 * https://opensource.org/licenses/BSD-3-Clause
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.tencent.angel.common;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.io.WritableComparable;

// TODO: 17/6/27 by zmyer
@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class Id implements WritableComparable<Id> {
    public static final String SEPARATOR = "_";
    protected int index;

    /** constructs an ID object from the given int */
    public Id(int index) {
        this.index = index;
    }

    protected Id() {
    }

    /** returns the int which represents the identifier */
    public int getIndex() {
        return index;
    }

    @Override
    public String toString() {
        return String.valueOf(index);
    }

    @Override
    public int hashCode() {
        return index;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null)
            return false;
        if (o.getClass() == this.getClass()) {
            Id that = (Id) o;
            return this.index == that.index;
        } else
            return false;
    }

    /** Compare IDs by associated numbers */
    public int compareTo(Id that) {
        return this.index - that.index;
    }

    public void readFields(DataInput in) throws IOException {
        this.index = in.readInt();
    }

    public void write(DataOutput out) throws IOException {
        out.writeInt(index);
    }
}
